Electric circuit breakers



March 24, 1959 2,879,356

J. C. HOLMES ELECTRIC CIRCUIT BREAKERS Filed Nov. 22, 1957 INVENTOR. JOHN C. HOLMES AT TORNEYS ir d St e P n The present invention relates to automatic electric circuit breakers andparticularly to such devices forv replacing standard screw-in fuse or cartridge plugs.

The primary object of this invention is'to provide a circuit breaker capable of being re-set after an overload has taken place causing the circuit breaker to open.

2,879,356 Patented Mar. 24;, 1959 ice cured to the upper end of the terminal 14 by soldering or riveting. An upper leg 28 of the member 26 is engaged by the lower side of the end 25 of the contact bar 23 under a spring tension existing between the contact bar- 23 and the U-shaped member 26, which will be more fully described later.

A latch 29 is formed as part of upper end 30 of the bimetal strip 21. The latch 29 normally engages upper surface 31 of a shoulder 32 which forms part of the plunger 16. The shoulder 32 is made of a metallic material to resist wear.

I A-further object of this invention is to provide a circuit breaker constructed so as to conveniently replace screwin, cartridge fuses, and other standard fuse plugs.

Another object of this invention is to provide a circuit breaker designed to eliminate the forming of electric arcs on the breaking of the circuit.

A still further object of this invention is to provide a circuit breaker that maintains a firm solid contact between the contact elements of the breaker until the overload takes place, when a complete separation therebetween will occur instantly.

Other objects and advantages will become apparent in the following specification when considered in the light of the attached drawings, in which:

Figure 1 is a vertical sectional view of the invention.

Figure 2 is a transverse sectional view, taken on the line 2-2 of Figure 1, looking in the direction of the arrows.

Figure 3 is a transverse sectional view, taken on the line 33 of Figure 1, looking in the direction of the arrows.

Figure 4 is a view similar to Figure 1 of a modified form of the invention shown partially broken away for convenience of illustration.

Figure 5 is a side elevation of another modified form of the invention shown partially broken away and in section.

Figure 6 is a fragmentary view similar to Figure 1 showing the contact mechanism thereof in open position.

Referring now to the drawings in detail wherein like reference numerals indicate like parts throughout the several figures, the reference character F indicates generally a circuit breaker constructed in accordance with the invention.

The circuit breaker F includes an insulated body B having an upper section 10 and a lower section 11 engaging at 12 and secured together by a metallic sleeve 13. A contact terminal 14 is located within lower tip 15 of the lower section 11.

A plunger 16 formed of insulation material extends through an opening 17 on the end of the section 10 opposite the section 11. The plunger 16 has its inner end 18 passing through an opening 19 in a partition 20 integrally formed in the section 10.

Fixedly mounted within the insulated body B is a bimetal strip 21. The strip 21 is fixedly secured within a socket 22 in the lower section 11 by means of being embedded within insulation. The lower end of the bi-metal strip 21 is connected to the terminal 14 by a spring bar 23 fixedly mounted thereto at 24. The opposite end 25 of the bar 23 contacting the U-shaped resilient metallic member 26. Lower leg 27 of member 26 is fixedly se- A spring 33 encompasses the plunger 16 and has its upper end engaging the lower side of the shoulder 32 and its lower end engaging the upper surface of the partition 20 thus placing an upward tension on the plunger 16 to lift the same when the latch 29 is released in the following manner.

The metallic sleeve 13 is connected to the upper end 30 of the bi-metal strip 21 by means of flexible connector 34. When electric current passes between the sleeve 13 and the terminal 14, it will pass through the bi-metal strip 21 from the sleeve 13 through the connector wire 34, down through the strip 21 across the metallic bar 23, into the resilient Uishaped member 26, into the contact 14, completing an electric circuit through the fuse socket within the fuse box.

When an overload takes place, the bi-metal strip 21 takes the position shown by the broken lines, Figure 1, releasing the latch 29 from the upper surface 31 of the shoulder 32 so that the spring 33 can raise the plunger 16 and allow the end 25 of the metal bar 23 to disengage itself from the upper leg 28 of the element 26, breaking the electric circuit extremely quickly without causing an arc to form.

The bi-metal strip 21 consists of two separate kinds of material 21A and 213. When the strip 21 is heated, the material 21A expands faster than the strip 21B. This causes the strip 21 to move to the broken line position in Figure l, releasing the latch 29. When the latch is released, the plunger 16 raises disengaging the bar 23 from the upper leg 28 of the U-shaped member 26 breaking the electric circuit through the circuit breaker F.

Referring to Figure 4, a modified form of embodiment is illustrated wherein the upper end 38 of the bi-metal strip 21' is longer and is anchored within a socket 39. The strip 21 operates slightly different than that shown in Figure 1, in that the metal 21A is on the opposite side of the strip 21' to that shown in Figure 1, due to the fact that the upper end of the strip 21 is anchored in the socket 39, the strip 21 will take the broken line position pulling the latch 29 away from the shoulder 32 of the plunger 16.

Referring to Figure 5, cartridge fuse C incorporates the invention in modified form. A lever 35 extends at right angles to the fuse C and forms part of a shoulder 32a. The lever 35 passes through a slot 37 on the side of the cartridge C terminating in a thumb button 36 used to reset the circuit breaker F.

The mode of operation of the circuit breaker P will now be described. Figure 1 illustrates the plunger 16 in lowered position with the end 25 of the contact bar 23 in contact with the leg 28 of the U-shaped terminal 26, making an electric connection between the threaded metallic sleeve 13, the connector 34 of the bi-metal strip 21, and out the terminal 14, completing an electric circuit through the fuse socket, not here shown.

When an overload takes place, the bi-metal strip 21 is brought into the broken line position by the difference of expansion between the materials 21A and the material 21B to cause the latch 29 to release itself from the shoulder 32, allowing the spring 33 to raise the plunger 16 and break the contact between the bar 23 and the U-shaped .7 3 v member 26'and the termina'l'14. When the bi-metal strip 21' cools ofifthe operator can push down on the'plunger 16, again latching the shoulder 32 under the latch 29. I Having thus described the .preferred embodiments of the'invent'ion, it should be understood that numerous structural modifications and adaptations may be resorted to, withoutdepartingj from the scope of the appended claims.

'What'is claimed is:

1. An electric circuit breaker comprising a body, a contact element fixedly secured axially of said body at one end thereof, a plunger, arranged in axial alignment total electric current of the circuit passes through said bimetallic latch heating saidlatc'h when overloadedto with said contact element'and supported in tsaid'body for axial reciprocation therein, said plunger having a handle forming portion thereof arranged to project from said body, a spring in said body engaging andnormally biasing saidplunger away from said contact, a firmly responsive bimetallic latch mounted insaid body generally parallel to said plunger for releasably securing said plunger against movement away from said contact, a spring contact bar secured to said latch at one end thereof and extending between said plunger and said contact element in spaced relation with respect to said contact element with said plunger ,in released position, said spring contact bar and said contact member being held in engagement by pressure from said plunger with said plunger secured by. said latch, andLmeans connecting the opposite end ofsaid bi metallic latch in the circuit to be broken whereby the move said latch releasing fsaid plunger, permitting disengagement of said spring contact bar from said contact element.

2. A device as claimed in claim 1 wherein means are provided on said body for threaded engagement of said body in an electric socket-.- I

3. A device-as claimedainclaim 1 wherein said body comprises a hollow cartridge having external contact portions on opposite-endsthereof'.

4. .Avdevice asclaimed in claim 1 wherein said contact element is providedwith a resilient portion biased in a direction forward. said'spring contact bar.

5. A device as claimed in claim 1 wherein a contact terminal is rigidly mounted in one end of said body and said contact member is mechanically and electrically connected thereto.

References Cited in the file of this patent- UNITED STATES. PATENTS Sundtv June 2'8,v 1949- 

